Digital Domain Media Group Inc., the Academy Award-winning company behind visual effects for films including "Titanic" and the Tupac Shakur hologram that debuted earlier this year, filed for Chapter 11 bankruptcy protection Tuesday and said its main operating unit would be sold.

Private investment firm Searchlight Capital Partners will pay $15 million for that unit, Digital Domain Productions, Digital Domain said. Founded by James Cameron, Scott Ross and Stan Winston, Digital Domain Productions has also created effects for such films as "Thor," "Star Trek," "X-Men: First Class," "The Watch," (left) and the "Transformers" franchise.

The company listed total debts of $214.9 million and total assets of $205 million.

According to documents filed with the Securities and Exchange Commission in August, it was unable to pay off $35 million in loans, though it then received extensions. DDMG reported $75 million in lost operating income in its 2011 annual report, and its stock price has dropped dramatically.

The company said last week it was shutting down its operations in Port St. Lucie, Fla. Also last week, DDMG chairman and CEO John Textor stepped down. The board of directors and interim COO Michael Katzenstein are now making company decisions.

Digital Domain shares closed at 55.4 cents on Monday, giving it a market value of $24 million. On May 1, the stock was at $9.16 for a market value of $400 million.